The purpose of this investigation is to assess virologic, environmental, and host factors that affect the progression of chronic hepatitis C virus (HCV) infection. The General Clinical Research Center at Johns Hopkins has been utilized to evaluate the principle outcome for this investigation, liver failure as determined by physical examination and liver biopsy. Since the beginning, NIH funding for this project has been received (1U19 AI 40035-01) and more than 30 liver biopsies have been completed. A preliminary analysis of the effect of HIV infection on HCV progression was published in the Journal of Infectious Diseases (Thomas, et al. 1996; 174: 690-95).